The popularity of consumer electronic devices such as portable computers, phones, pagers, organizers and the like has derived, in part, from the ability of manufacturers to provide these devices in compact forms suitable for portable use; that is, these electronic products have been reduced in size so they can be conveniently transported. In this regard, space considerations are of paramount importance in the design and assembly thereof.
One particular area where space allocation and savings are a significant consideration is in housings for printed circuit boards (PCB's) for communication products. In these as well as other electronic consumer products, the next generation for these lines are rarely any further than one or two years down the road, and numerous derivative designs typically are launched off the original platform. In addition, oftentimes changes are necessary to provide product variations that operate in different countries and/or on different infrastructures. Due to component variations between product versions, it can become necessary to move the PCB's up or down within the housing to provide the proper component clearances on the top and bottom of the final printed circuit assembly. Cycle times and development costs can become critical factors as to whether the changes associated with a different PCB placement are feasible.
Typically, stand-off bosses or bracket-type locating members are provided to which the PCB is mounted, the members being either integrally formed with the PCB housing or as separate components for being attached thereto. These types of mounting members are used to mount the PCB in a single predetermined position in the housing and thus do not allow for the height or z-axis location of the PCB to be changed without costly and time-consuming design changes (e.g. tooling changes, material scrap and/or PCB relayout activity). With distinct components, it is generally true that there is insufficient room in the housing for different types or sizes of bosses or brackets to be attached in the housing for changing the position of the PCB without complicated redesign and/or relayout of the internal configuration of the various housed components.
In PCB modules, such as those used for RF products, the module housing is designed to be placed in an outer housing of a host device. These modules generally have a very low profile with a height or thickness in the z-direction on the order of approximately one-inch. The PCB used in these modules can be located intermediate the upper and lower covers of the module leaving approximately 1/4" above and below the PCB for the module components such as where the PCB is two-sided with circuit patterns on both upper and lower surfaces thereof. To lower costs for the PCB as by only etching a circuit pattern on one side thereof and assemble and test components placed on that side, i.e. the PCB upper surface, requires that there be more room for the components above the PCB upper surface; thus, the position or height of the PCB in the module has to be lowered such as to provide 3/4" of clearance above the PCB between its upper surface and the upper cover of the module. To change the PCB position in narrow width modules such as for populating only one side or the other of a PCB with components, either the mounting standoffs or the configuration of the module housing itself has to be changed including the considerable expense associated with both options. Changing the standoffs without changing the housing may not be practical or possible due to the tight clearances present in module housings.
When the PCB mounting arrangement is too complicated to change, expensive redesigns of the configuration of the housing are necessary to allow the PCB position to be adjusted such as where the original circuitry design or platform is to be maintained in the product, albeit used with different components, as previously described. To redesign the housing requires that its tooling be revamped or replaced which can be very time consuming and expensive. In today's market place, undue time delays in bringing these derivative products to the consumers is highly undesirable given the aggressive time-to-market goals typically present. In addition, oftentimes altering the configuration of the housing is not an option. This is because the outer housing dimensions are usually fixed by standard form factors such as the PCMCIA or Device Bay specification, leaving only the internal configuration of the various components to be modified to accommodate the required adjustments to the position of the PCB. Where the product utilizes more than one PCB, the above-noted problems are exacerbated, especially where it is desired to adjust the position of both boards in a housing. A further complicating factor in changing the position and thus the mounting of a PCB is the need to pass the vibration and shock tests to which the mounting system will be subjected so that for every different configuration, in addition to the costs associated with redesigning and retooling for these changes, there is the need to undergo additional rounds of testing for each subsequent product version.
Accordingly, there is a need for a mounting system that allows for adjustments to be made in the position of a element, e.g. printed circuit board, supported thereby with a minimum of time and expense. In particular, a mounting system for a printed circuit board is needed where changes in the position of the PCB can be made in a relatively quick and easy, low-cost manner without necessitating changes to the mounting standoffs and/or the configuration of the housing containing the PCB.